Cardiovascular disease (CVD) is the leading cause of death in women, and currently kills more women than men in the U.S. due to the greater burden of cardiovascular risk after menopause. Depression increases risk for CVD by two-fold. Understanding the depression-CVD link has particular relevance for women since they suffer from depression at a rate twice that of men. Estrogen (E2) withdrawal not only increases cardiovascular risk in women, but is also involved in depression. The planned study will examine the biological mediators of risk that are common to both CVD and depression (inflammation, endothelial dysfunction, cardiac autonomic dysregulation, and metabolic disturbance) within the context of E2 withdrawal during the perimenopause. Heightened cardiovascular, neuroendocrine and inflammatory reactivity to stress also define a profile of risk and adversely impacts the mediators of risk described above. While E2 is associated with beneficial effects on the mediators of risk common to depression and CVD and on stress reactivity, and is also effective in reducing depressive symptoms, there is substantial variance in both the cardioprotective and antidepressant responses to E2. The planned research intends to identify a profile of risk that would predict the greatest benefits of E2 in the prophylaxis of the progression of cardiovascular risk and appearance of depression in perimenopausal women. Based on the shared mediators of risk for CVD and depression, we predict that perimenopausal women with histories of recurrent depression will show greater progression of cardiovascular risk and suffer from more depression over 12 months than never depressed women, and show cardiovascular benefit of E2. A total of 320 perimenopausal women (45-55 years of age; STRAW stage-1) who are eligible candidates for E2 will be studied. Based on SCID interview, one half (n=160) will have a history of recurrent depression (2+ depressive episodes, 1+ must be major depression), but in remission (>2 yrs and with current CES-D score d 8) and 160 will be recruited as never depressed perimenopausal women (also CES-D d 8). Following medical and psychiatric evaluation, including assessment of lifetime trauma exposure, women will be tested for baseline cardiovascular risk profiles which include: 1) Cardiac Autonomic Tone - defined by baroreceptor sensitivity involving the non-invasive measurement of HR and beat-to-beat change in BP; 2) Stress Reactivity - based on a composite score involving cardiovascular (blood pressure and vascular resistance), neuroendocrine (cortisol), and inflammatory (IL-6) responses to the Trier Social Stress Test; 3) Endothelial Function - based on ultrasound measurement of flow mediated dilatation of the brachial artery during reactivity hyperemia; and 5) Metabolic Risk - determined based on meeting standard criteria for the metabolic syndrome or exhibiting insulin resistance in response to the oral glucose tolerance test. Using double-blind procedures, subjects will then be randomized to either transdermal 172-E2 (100ug/day) or placebo for 12 months, and micronized progesterone (P) will be given every 3 months to women on active ERT (placebo P given on 2 out of 3 months) and placebo P will be given every month to women on placebo ERT. Subjects will be assessed at regular intervals during the intervention for depression, compliance, vitals, and side effects. At months 6 and 12 of the treatment period, all cardiovascular procedures conducted at the baseline assessment will be repeated. This is a mechanistic study designed to examine the predictors (history of recurrent depression) and moderators (trauma exposure) of cardiovascular risk progression in untreated perimenopausal women over 12 months, and the mediators (stress reactivity profile) of the beneficial effects of E2 treatment on depression and cardiovascular risk. The results of this study are intended to identify potential targets for behavioral or biological intervention and provide mechanistic hypotheses that can be tested in depressions that occur during other stages of life as well as help advance the goals of individualized medicine.